1 // SPDX-License-Identifier: GPL-2.0 2 /* 3 * Raspberry Pi 4 firmware reset driver 4 * 5 * Copyright (C) 2020 Nicolas Saenz Julienne <nsaenzjulienne@suse.de> 6 */ 7 #include <linux/delay.h> 8 #include <linux/device.h> 9 #include <linux/module.h> 10 #include <linux/of.h> 11 #include <linux/platform_device.h> 12 #include <linux/reset-controller.h> 13 #include <soc/bcm2835/raspberrypi-firmware.h> 14 #include <dt-bindings/reset/raspberrypi,firmware-reset.h> 15 16 struct rpi_reset { 17 struct reset_controller_dev rcdev; 18 struct rpi_firmware *fw; 19 }; 20 21 static inline struct rpi_reset *to_rpi(struct reset_controller_dev *rcdev) 22 { 23 return container_of(rcdev, struct rpi_reset, rcdev); 24 } 25 26 static int rpi_reset_reset(struct reset_controller_dev *rcdev, unsigned long id) 27 { 28 struct rpi_reset *priv = to_rpi(rcdev); 29 u32 dev_addr; 30 int ret; 31 32 switch (id) { 33 case RASPBERRYPI_FIRMWARE_RESET_ID_USB: 34 /* 35 * The Raspberry Pi 4 gets its USB functionality from VL805, a 36 * PCIe chip that implements xHCI. After a PCI reset, VL805's 37 * firmware may either be loaded directly from an EEPROM or, if 38 * not present, by the SoC's co-processor, VideoCore. rpi's 39 * VideoCore OS contains both the non public firmware load 40 * logic and the VL805 firmware blob. This triggers the 41 * aforementioned process. 42 * 43 * The pci device address is expected is expected by the 44 * firmware encoded like this: 45 * 46 * PCI_BUS << 20 | PCI_SLOT << 15 | PCI_FUNC << 12 47 * 48 * But since rpi's PCIe is hardwired, we know the address in 49 * advance. 50 */ 51 dev_addr = 0x100000; 52 ret = rpi_firmware_property(priv->fw, RPI_FIRMWARE_NOTIFY_XHCI_RESET, 53 &dev_addr, sizeof(dev_addr)); 54 if (ret) 55 return ret; 56 57 /* Wait for vl805 to startup */ 58 usleep_range(200, 1000); 59 break; 60 61 default: 62 return -EINVAL; 63 } 64 65 return 0; 66 } 67 68 static const struct reset_control_ops rpi_reset_ops = { 69 .reset = rpi_reset_reset, 70 }; 71 72 static int rpi_reset_probe(struct platform_device *pdev) 73 { 74 struct device *dev = &pdev->dev; 75 struct rpi_firmware *fw; 76 struct device_node *np; 77 struct rpi_reset *priv; 78 79 np = of_get_parent(dev->of_node); 80 if (!np) { 81 dev_err(dev, "Missing firmware node\n"); 82 return -ENOENT; 83 } 84 85 fw = rpi_firmware_get(np); 86 of_node_put(np); 87 if (!fw) 88 return -EPROBE_DEFER; 89 90 priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL); 91 if (!priv) 92 return -ENOMEM; 93 94 dev_set_drvdata(dev, priv); 95 96 priv->fw = fw; 97 priv->rcdev.owner = THIS_MODULE; 98 priv->rcdev.nr_resets = RASPBERRYPI_FIRMWARE_RESET_NUM_IDS; 99 priv->rcdev.ops = &rpi_reset_ops; 100 priv->rcdev.of_node = dev->of_node; 101 102 return devm_reset_controller_register(dev, &priv->rcdev); 103 } 104 105 static const struct of_device_id rpi_reset_of_match[] = { 106 { .compatible = "raspberrypi,firmware-reset" }, 107 { /* sentinel */ } 108 }; 109 MODULE_DEVICE_TABLE(of, rpi_reset_of_match); 110 111 static struct platform_driver rpi_reset_driver = { 112 .probe = rpi_reset_probe, 113 .driver = { 114 .name = "raspberrypi-reset", 115 .of_match_table = rpi_reset_of_match, 116 }, 117 }; 118 module_platform_driver(rpi_reset_driver); 119 120 MODULE_AUTHOR("Nicolas Saenz Julienne <nsaenzjulienne@suse.de>"); 121 MODULE_DESCRIPTION("Raspberry Pi 4 firmware reset driver"); 122 MODULE_LICENSE("GPL"); 123